Acquisition, Dispositions and Atlantic Restructuring Charges - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			12 Months Ended		3 Months Ended		1 Months Ended
	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2013 Vessel	Sep. 30, 2013 Charter Fleet Business	Sep. 30, 2012 Charter Fleet Business	Dec. 31, 2011 Charter Fleet Business	Mar. 19, 2012 Charter Fleet Business Vessel	Jun. 30, 2013 Maximum	Jun. 30, 2013 Minimum	Mar. 19, 2012 Secunda International Limited Vessel
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total purchase consideration			$ 9,000,000
Purchase consideration - cash			6,000,000
Purchase consideration - restricted shares			313,580
Number of vessels held for sale			4
Proceeds from sale of discontinued assets		32,000,000
Gain on sale of the Bold Endurance		12,500,000
Number of vessels operated							10
Number of vessels										14
Cash Proceeds from sale of business				61,000,000
Gain on sale				300,000	257,000
Write-down of charter fleet business						22,000,000
Expected restructuring cost								65,000,000	55,000,000
Restructuring cost incurred	$ 4,000,000		$ 19,500,000